Stern report: the key points

· All countries will be affected by climate change, but the poorest countries will suffer earliest and most.

· Average temperatures could rise by 5C from pre-industrial levels if climate change goes unchecked.

· Warming of 3 or 4C will result in many millions more people being flooded. By the middle of the century 200 million may be permanently displaced due to rising sea levels, heavier floods and drought.

· Warming of 4C or more is likely to seriously affect global food production.

· Warming of 2C could leave 15-40% species facing extinction.

· Before the industrial revolution level of greenhouse gases in the atmosphere was 280 parts per million (ppm) CO2 equivalent (CO2e); the current level is 430ppm CO2e. The level should be limited to 450-550ppm CO2.

· Anything higher would substantially increase risks of very harmful impacts. Anything lower would impose very high adjustment costs in the near term and might not even be feasible.

· Deforestation is responsible for more emissions than the transport sector.

· Three elements of policy are required for an effective response: carbon pricing, technology policy and energy efficiency.

· Carbon pricing, through taxation, emissions trading or regulation, will show people the full social costs of their actions. The aim should be a global carbon price across countries and sectors.

· Emissions trading schemes, like that operating across the EU, should be expanded and linked.

· Technology policy should drive the large-scale development and use of a range of low-carbon and high-efficiency products.

· Globally, support for energy research and development should at least double; support for the deployment of low-carbon technologies should be increased my up to five times.

· International product standards could be introduced.

· Large-scale international pilot programmes to explore the best ways to curb deforestation should be started very quickly.

· Climate change should be fully integrated into development policy, and rich countries should honour pledges to increase support through overseas development assistance.

· International funding should support improved regional information on climate change impacts.

· International funding should go into researching new crop varieties that will be more resilient to drought and flood.

Economic impacts

· The benefits of strong, early action considerably outweigh the costs.

· Unabated climate change could cost the world at least 5% of GDP each year; if more dramatic predictions come to pass, the cost could be more than 20% of GDP.

· The cost of reducing emissions could be limited to around 1% of global GDP; people could be charged more for carbon-intensive goods.

· Each tonne of CO2 we emit causes damages worth at least $85, but emissions can be cut at a cost of less than $25 a tonne.

· Shifting the world onto a low-carbon path could eventually benefit the economy by $2.5 trillion a year.

· By 2050, markets for low-carbon technologies could be worth at least $500bn.

· What we do now can have only a limited effect on the climate over the next 40 or 50 years, but what we do in the next 10-20 years can have a profound effect on the climate in the second half of this century.